A team composed of Li Gongxiu (third from left), Chen Chuchu (fourth from left), Lin Kechun (sixth from left) and others go to Hainan province to establish a radioactive natural background workstation. [Photo/ibp.cas.cn]

Research on the radioactivity background in China. [Photo/ibp.cas.cn]

The No. 21 task group of the Institute of Biophysics visits the nuclear explosion site for the sixth time to conduct animal experiments in 1976. [Photo/ibp.cas.cn]